Housing Status, Cancer Care, and Associated Outcomes Among US Veterans

Key Points Question What is the association between housing status and cancer outcomes among patients treated in the US Department of Veterans Affairs (VA) health system? Findings In this cohort study of 109 485 veterans diagnosed with lung, colorectal, or breast cancer who received VA care between 2011 and 2020, homelessness was associated with increased rates of all-cause mortality for lung and colorectal cancers. Meaning These findings suggest that differences in survival based on housing status exist, but VA health systems may offer insights to improve oncologic outcomes for individuals experiencing homelessness elsewhere.


Introduction
Individuals experiencing homelessness have worse overall health status relative to the general population owing to a higher burden of chronic health conditions, increased rates of injuries, and markedly increased risk of premature mortality. 1As this population ages, there will be an increased need to provide care for chronic medical problems, including cancer. 1,2[5] Prior studies have highlighted cancer as a leading cause of death in patients experiencing homelessness who are aged older than 50 years. 6,7search evaluating the consequences of housing status on cancer treatment has focused on screening.10][11][12][13] Cancer outcomes, including stage at diagnosis, surgical outcomes, and mortality rates after diagnosis, are understudied in patients experiencing homelessness.One study examined 361 cancers among adults experiencing homelessness from a single US center and found that colorectal, breast, and oropharyngeal cancers were diagnosed at more advanced stages in these individuals and that they had higher rates of cancer mortality. 14To expand our understanding of oncologic care, we examined data from the US Department of Veterans Affairs (VA) health system to characterize the diagnosis, treatment, surgical outcomes, and mortality of patients receiving VA care for lung, colorectal, or breast cancer who were experiencing homelessness compared with individuals with housing.We hypothesized that veterans experiencing homelessness would have later stages at diagnosis, less overall cancer-directed therapy, poorer surgical outcomes, and higher rates of mortality than veterans with housing.The VA offers the opportunity to address these questions because it has a robust data infrastructure and has recorded housing status and addressed homelessness among beneficiaries for over a decade. 15

Overall Design
This retrospective cohort study used a national sample from the VA to assess whether housing status may be associated with stage at diagnosis, treatment, and outcomes for lung, colorectal, and breast cancers.The Stanford Institutional Review Board reviewed and approved this study and its protocol, with a waiver of informed consent because of minimal risk to patients.The study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline.

Study Population
We used the VA Corporate Data Warehouse (CDW) Oncology Domain, which abstracts data from local tumor registries, to identify all veterans with a diagnosis of lung, colorectal, or breast cancer who received VA care between October 1, 2011, through September 30, 2020.The CDW Oncology Domain is the predecessor of the VA Central Cancer Registry, ensuring complete documentation of cancer burden in the VA.We linked Veterans Affairs Surgical Quality Improvement Program (VASQIP) data to examine surgical outcomes and complications.We focused on lung, colorectal, and breast cancers because these have clear screening guidelines, are common, and have surgery as a key component of treatment.

Exposure
We classified veterans as experiencing homelessness if they had any indicators of homelessness in outpatient visits, clinic reminders, diagnosis codes, or the Homeless Operations Management

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Housing Status, Cancer Care, and Associated Outcomes Among US Veterans Evaluation System 15,16 (eAppendix in Supplement 1) in the 12 months preceding diagnosis with no subsequent evidence of stable housing (before diagnosis).Use of these multiple sources has been shown to identify more veterans experiencing homelessness than relying on any one indicator; as such, it is considered best practice to use all of the indicators to fully capture homelessness. 16After diagnosis, we characterized patients as persistently experiencing homelessness if they had no evidence of stable housing in the 12 months after diagnosis.We characterized patients experiencing homelessness as having gained housing if they subsequently had evidence of stable housing in the 12 months after diagnosis.We defined stable housing in this context if a patient responded that they had stable housing on the Health Factors Survey, which is administered in both outpatient and inpatient settings.

Measurements Diagnosis, Treatment Path, and Cancer Outcomes
We obtained information from the VA CDW Oncology Domain on diagnosis date, cancer type, follow-up status, presentation at a cancer conference, chemotherapy type, receipt of surgery, radiation type, duration of radiation treatment, and receipt of palliative care.We obtained information on days from diagnosis to the start of chemotherapy, to the most definitive surgery, and to the start of radiation.

Mortality and Censoring
We obtained mortality data from the CDW Oncology Domain and the VA Vital Status file.We defined survival time as the interval between the initial diagnosis and death from any cause.We censored veterans at the time they were documented as lost to follow-up in the CDW Oncology Domain or on October 1, 2022, when we accessed the data.We also censored veterans who changed housing status in the 12 months after diagnosis at the time of housing status change.

Surgical Management
We queried the VASQIP database to ascertain information on definitive cancer surgeries.The VASQIP collects data on procedures occurring at the VA only and only collects a subset of those procedures. 17 the 44 138 surgeries identified in the VA Central Cancer Registry, 69% occurred at the VA and 84% of these surgeries (n = 25 737) were assessed by the VASQIP.We obtained data on emergent case status, admission status, length of stay, and postoperative complications.

Additional Covariates
We obtained patient-level demographic data from the CDW Patient Domain, including age, sex, race, ethnicity, and marital status.Data on veteran race (American Indian or Alaska Native, Asian, Black or African American, Native Hawaiian or Other Pacific Islander, White, or multiple races) and ethnicity (Hispanic or Latino or not) were obtained from the CDW, which is primarily based on patient selfreport and has been shown to be highly accurate for assessing race and ethnicity in VA data. 18We assessed race and ethnicity in this study given the ways in which structural racism and discrimination reinforce poverty and contribute to homelessness.Patient-level clinical characteristics included comorbidity burden (using the Charlson Comorbidity Index), smoking status, alcohol use, and stage at diagnosis.We obtained information on the facility district where care was received.

Major Outcomes
The major outcomes explored were as follows: (1) treatment course, including stage at diagnosis; (2)   surgical outcomes, including length of stay and major complications; (3) overall survival by cancer type; and (4) hazard ratios for overall survival in a model adjusted for measured covariates.

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Housing Status, Cancer Care, and Associated Outcomes Among US Veterans

Statistical Analysis
We conducted separate analyses for lung, colorectal, and breast cancers.We first performed unadjusted analysis comparing baseline characteristics and outcomes among patients with housing and those experiencing homelessness.We then developed Kaplan-Meier curves to display unadjusted mortality by cancer type.Finally, we created multivariable Cox proportional-hazard regression models to compare hazard ratios of mortality for each group for each cancer type, adjusting for age at diagnosis, sex, stage at diagnosis, race, ethnicity, marital status, facility location, and behavioral or physical health comorbidities.We divided the models into 2 distinct time periods: the first 3 months after diagnosis and beyond 3 months.We hypothesized that differences in populations with housing and individuals experiencing homelessness would differ based on time after diagnosis (with patients experiencing homelessness more likely to have adverse outcomes further out from diagnosis as follow-up and care coordination becomes more important) and because of evidence of nonproportionality in the early part of the unadjusted survival curves.We used a directed acyclic graph based on a literature review to determine the final set of covariates included in the model.Two-tailed P < .05 was considered statistically significant.All data analysis was performed in R, version 4.1.2(R Foundation for Statistical Computing).Data analysis was performed from February 13 to May 9, 2023.

Population Characteristics
There were 109 485 veterans diagnosed with cancer in our sample, with a mean (SD) age of 68.5 (9.7) years.Men comprised most of the study population (92%) compared with women (8%).A total of 1% of patients identified as American Indian or Alaska Native, 0.4% as Asian, 18% as Black or African American, 1% as Native Hawaiian or Other Pacific Islander, 79% as White, and 1% as being of multiple races.A total of 4% of veterans reported being of Hispanic ethnicity.There were 104 129 veterans (95%) with housing and 5356 (5%) experiencing homelessness at the time of cancer diagnosis.Of the cohort experiencing homelessness, 1031 (19%) gained housing within the first year after diagnosis and were censored from the survival analysis at the time of gaining housing.Breast cancer accounted for 6378 diagnoses (6%), colorectal cancer for 28 537 (26%), and lung cancer for 74 570 (68%).The group experiencing homelessness had a higher proportion of Black veterans (37% vs 17%) and was younger (mean [SD], 63.1 [8.7] vs 68.7 [9.6] years) than the group with housing.
Veterans were treated at facilities across the US (Table 1 and eTable 4 in Supplement 1).

Unadjusted Analysis
Patients experiencing homelessness were notably younger at diagnosis for all 3 cancers evaluated, with a mean (SD) age at diagnosis of 64.4 (7.8) vs 69.8 (8.3) years for lung cancer, 61.8 (9.5) vs 68.1 (10.9) years for colorectal cancer, and 54.6 (9.1) vs 58.8 (11.7) years for breast cancer.For all 3 cancer types, patients experiencing homelessness were more commonly Black compared with their counterparts with housing (lung: 35% vs 15%; colorectal: 41% vs 20%; and breast: 45% vs 30%).A greater proportion of individuals experiencing homelessness were treated in the Pacific region for lung (24% vs 15%) and colorectal (30% vs 17%) cancers.For all 3 cancers evaluated, patients experiencing homelessness had similar Charlson Comorbidity Index scores compared with patients with housing, although the composition of their comorbidities differed.Patients experiencing homelessness more commonly had depression, bipolar disorder, or other mood disorders and more commonly reported tobacco use as well as alcohol use and liver disease.However, these patients less commonly reported diabetes, peripheral vascular disease, and cerebrovascular disease.These patients had more inpatient admissions, emergency department visits, and primary care visits in the year before diagnosis compared with patients with housing across cancer types (Table 1).

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Housing Status, Cancer Care, and Associated Outcomes Among US Veterans b Summed subset numbers may not add to category totals in the case of missing data.

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Housing Status, Cancer Care, and Associated Outcomes Among US Veterans

Treatment Course
There were no statistically significant differences in stage at diagnosis in lung or breast cancer (Table 2) between patients by housing status.However, a higher proportion of patients experiencing homelessness presented with stage IV colorectal cancer compared with patients with housing (22% vs 19%; P = .02).There was no difference in treatment status for colon and lung cancers (eg, if treatment was given, no treatment was given, or active surveillance was pursued), but patients experiencing homelessness were more likely to have no treatment given in breast cancer (7% vs 4%).
Similar proportions of patients in both groups were lost to follow-up in all cancer types.The type of

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Housing Status, Cancer Care, and Associated Outcomes Among US Veterans chemotherapy given was not statistically different between groups with lung cancer, although palliative chemotherapy was more common in patients with colorectal cancer experiencing homelessness (8% vs 6%).A lower proportion of patients experiencing homelessness underwent surgery for colorectal cancer (72% vs 77%), whereas similar proportions in both groups received definitive oncologic surgery for lung and breast cancer.For those who underwent colorectal surgery, a higher proportion of patients experiencing homelessness had less than 12 lymph nodes examined in oncologic surgery compared with patients with housing (60% vs 55%).Similar proportions in both groups received palliative care in all 3 cancers studied.Greater proportions of patients experiencing homelessness and diagnosed with colorectal or lung cancer were presented at multidisciplinary cancer conferences compared with individuals with housing.

Time to Treatment
The

Surgical Outcomes
We included 25 737 operations in our analysis, 1225 (5%) of which were among patients experiencing homelessness.There was no difference in the proportion of surgical procedures captured in the VASQIP by housing status (eTable 1 in Supplement 1).Demographics of patients included in the analysis of surgical outcomes are displayed in eTable 2 in Supplement 1.There was no difference in the incidence of emergent operations, postoperative admissions, or any postoperative complications (including surgical site infection, urinary tract infection, myocardial infarction, stroke, or deep venous thrombosis) between patient groups by housing status.Patients experiencing homelessness had a higher rate of pulmonary emboli after lung cancer operation (1.3% vs 0.6%).In addition, patients experiencing homelessness had notably longer mean (SD) lengths of stay for all cancer types (lung: These patients were also less likely to be discharged to the community in all cancer types studied (Table 4).

Overall Survival
In the unadjusted survival curve for all-cause mortality for breast cancer, lower survival rates were observed for patients experiencing homelessness (eFigure in Supplement 1).Patients with lung or colorectal cancer and experiencing homelessness did not have statistically significantly different survival curves compared with patients with housing.

Adjusted Survival
After adjusting for age at diagnosis, sex, stage at diagnosis, race, ethnicity, marital status, facility location, and comorbidities, patients experiencing homelessness had higher rates of mortality after

Discussion
This study examined US veterans receiving VA care who were diagnosed with lung, colorectal, or breast cancer between 2011 and 2020.We observed that patients experiencing homelessness had 1.1 to 1.3 times the risk of mortality for lung and colorectal cancers beyond 3 months after diagnosis compared with patients with housing.We did not observe any statistically significant differences in adjusted hazard ratios for death in patients with breast cancer.These findings differ in magnitude from other research examining cancer outcomes in this population, which reported 1.7 to 2.3 times the rate of lung cancer mortality and 1.4 to 1.7 times the rate of colorectal cancer mortality in patients experiencing homelessness compared with patients with housing (eTable 3 in Supplement 1). 14,19We also observed that patients experiencing homelessness were more commonly diagnosed with Length of stay, mean (SD), d Return to the operating room 552 (5) 23 (4)  .48888 (8) 43 (7)  .81179 (8) 11 (10)  .48 Any postoperative complication 1365 (13)  64 (12)  .792187 (19)  119 (20)  .4282 (4) 5 (5)  .61 Wound disruption 17 (0.

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Housing Status, Cancer Care, and Associated Outcomes Among US Veterans metastatic colorectal cancer than patients with housing (22% vs 19%), but they were diagnosed at similar lung and breast cancer stages.Although this finding is consistent with other VA studies, 20 it differs from other settings.For example, a study from the Boston Health Care for the Homeless Program reported that greater than 40% of colorectal cancers in patients experiencing homelessness were metastatic on presentation (compared with <20% of patients with housing) and almost 70% of breast cancers in these patients were locally advanced on presentation. 14Finally, we observed that veterans experiencing homelessness received similar cancer treatment to veterans with housing, with similar rates of loss to follow-up, similar overall times to treatment initiation, and similar rates of postoperative complications.
These more attenuated findings may be related to the unique strengths of the VA health system, which reduces financial barriers to care by providing health care to all members regardless of insurance status.We observed similar treatment patterns between patient groups regardless of housing status, which suggests that access to oncologic care may not be as large of a barrier for patients in the VA system experiencing homelessness compared with other settings.We saw some evidence of differences in care provided for patients experiencing homelessness, including being less likely to have more than 12 lymph nodes examined during surgery for colorectal cancer, waiting substantially longer for definitive surgery for lung cancer, and waiting longer to initiate radiation therapy for colorectal and breast cancers.However, these differences were less pronounced than in other settings, in which patients with cancer who were also experiencing homelessness more commonly had treatment delays, 21,22 missed appointments, 21 and incomplete treatment. 21However, there may be unmeasured differences in therapy completion and adherence to guidelineconcordant care, which could contribute to the observed differences in outcomes.There may be many reasons for differential adherence to care guidelines at both the individual (patient and physician) and system levels, which ought to be further explored qualitatively.
Our findings related to stage at diagnosis may reflect improved access to primary care and screening in VA-treated patients experiencing homelessness compared with non-VA settings, particularly for lung and breast cancers.In our cohort, both patient groups had similar access to primary care in the year before diagnosis.However, a greater proportion of patients experiencing homelessness presented with metastatic colorectal cancer, which may be related to barriers in timely screening.Barriers described in other vulnerable groups, including lower rates of physician recommendation, limited health literacy, and distrust in the health care system, likely apply to patients experiencing homelessness as well. 23Additionally, other social and structural barriers unique to patients experiencing homelessness (including lack of private bathrooms and competing priorities) may be important to address as well. 24,25en investigating outcomes after cancer surgery, we observed longer lengths of stay for individuals experiencing homelessness.However, this difference was smaller than observed postsurgically in other settings, 26 which may be related to supportive discharge options available to patients experiencing homelessness cared for at the VA.In our study, a higher proportion of patients experiencing homelessness were discharged to noncommunity settings, which is consistent with other surgical literature at the VA. 27e VA has made addressing veteran homelessness a priority since 2009 28 by investing in dedicated housing resources to meet veteran needs, including homelessness prevention, rapid rehousing, rental subsidies, and permanent supportive housing. 29This commitment has resulted in a 45% reduction in counts of veterans experiencing homelessness on a single night between 2009 and 2017 (compared with much smaller reductions in the overall US population experiencing homelessness). 30,31In our cohort, we observed that almost 20% of veterans experiencing homelessness gained housing after cancer diagnosis.[23][24][25] Of note, in this study, a markedly higher proportion of individuals experiencing homelessness were Black compared with individuals with housing (37% vs 17%).This difference is consistent with

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Housing Status, Cancer Care, and Associated Outcomes Among US Veterans the overall demographics of individuals experiencing homelessness in the US, with Black individuals overrepresented due to structural racism. 32Given that there are well-documented racial disparities in cancer care and oncologic outcomes, there may have been interaction between race and housing status that was associated with overall outcomes, which should be explored in further studies. 33nally, we observed that veterans experiencing homelessness were diagnosed at younger ages (by 4-7 years) for all cancers studied.This finding aligns with other literature highlighting earlier onset of chronic diseases in populations experiencing homelessness, 34 and it may prompt clinicians to have a higher index of suspicion for malignant neoplasm in younger patients with appropriate symptoms who are experiencing homelessness.
Many factors contribute to the likelihood of survival after a cancer diagnosis, including biological, environmental, behavioral, health care, economic, political, and social determinants. 35ck of housing is a critical factor that interacts across many of these domains with consequences on health outcomes-ranging from poor access to ambulatory care, 36 to bias and stigma, to difficulty navigating complex health care systems due to competing priorities, 37 and to vulnerability to external forces such as law enforcement or shelter requirements. 38However, this individual-level social determinant of health has been understudied, particularly in cancer, in part because of the lack of systematic documentation of housing status.The VA has one of the most robust documentation systems of homelessness in the country, due to multiple different layers of inquiry and reporting in both the inpatient and outpatient settings. 39This contrasts with other administrative mechanisms of reporting housing, which rely primarily on zip codes and International Classification of Diseases, Tenth Revision, Clinical Modification Z codes, both of which have been shown to be markedly underused. 40A more nuanced understanding of the consequences of housing status on cancer care and outcomes will only be possible with more complete documentation in other health systems.

Limitations
This study has certain limitations.Our sample only included veterans using VA health care.Therefore, the results may not be generalizable to other veterans experiencing homelessness who are not in the VA system and to nonveteran populations experiencing homelessness.Depending on the volume and expertise of the center, veterans may seek community care for certain cancers (particularly breast cancer).However, we sought to understand the cancer outcomes and care experiences of veterans cared for in the VA system.Our evaluation of surgical outcomes is limited to only a subset of procedures performed at the VA.[37][38][39][40]

Conclusions
The findings of this cohort study suggest that differences in oncologic outcomes in breast, colorectal, and lung cancers between VA patients experiencing homelessness and those with housing are present but small.This result differs from findings in other settings.There may be important lessons to learn from the VA that other health systems can adopt to improve oncologic outcomes for patients experiencing homelessness.

Table 1 .
Demographic Characteristics of Veterans Diagnosed With Lung, Colorectal, or Breast Cancer, Stratified by Housing Status a a Unless indicated otherwise, data are presented as the No. (%) of patients.Percentages may not total 100 owing to rounding.eTable 4 in Supplement 1 provides additional demographic features.

Table 2 .
Stage at Diagnosis and Treatment Course, Stratified by Veteran Housing Status a Abbreviation: NA, not available.aUnlessindicated otherwise, data are presented as the No. (%) of patients.Percentages may not total 100 owing to rounding.bSummed subset numbers may not add to category totals in the case of missing data.
median time from diagnosis to chemotherapy start was similar for both patient groups for lung, overlapped.The median (IQR) time to definitive surgery for lung cancer was longer for patients experiencing homelessness (57[14-96]vs 48 [0-81] days), with overlap in the IQRs (Table3).

Table 3 .
Median Time From Diagnosis to Treatment, Stratified by Veteran Housing Status a All P values are derived from Wilcoxon rank-sum tests.

Table 4 .
Outcomes Following Definitive Oncologic Operation, Stratified by Veteran Housing Status a

Table 5 .
Unadjusted and Adjusted Cox Proportional Hazards Regression Models for All-Cause Mortality a a Patients who changed housing status after diagnosis were censored at the time of housing status change.bAdjusted for age at diagnosis, sex, stage at diagnosis, race, ethnicity, marital status, facility location, and mental or physical health comorbidities.

SUPPLEMENT 1. eAppendix.
Determination of Housing Status in US Department of Veterans Affairs Health System Data eTable 1. Proportion of All Procedures Identified in the Veterans Affairs Surgical Quality Improvement Program (VASQIP) eTable 2. Demographics of Patients Included in Surgical Outcomes Analysis eFigure.Kaplan-Meier Curves for All-Cause Mortality for Lung, Colorectal, and Breast Cancer, Stratified by Housing Status eTable 3. Comparison of Mortality Differences Between Unhoused and Housed Patients With Cancer in Other Studies eTable 4. Demographic Characteristics of Veterans Diagnosed With Lung, Colorectal, and Breast Cancer Stratified by Housing Status